add support for socketoption sctp_auth_active_key

gtests/net/packetdrill/lexer.l

gtests/net/packetdrill/parser.y

gtests/net/packetdrill/run_system_call.c

gtests/net/packetdrill/script.c

gtests/net/packetdrill/script.h

gtests/net/packetdrill/symbols_freebsd.c

...ts/bsd/sctp/api_tests/getsockopt/sctp_auth_active_key.pkt

...sd/sctp/api_tests/getsockopt/sctp_fragment_interleave.pkt

...ts/net/packetdrill/tests/bsd/sctp/api_tests/run-all-tests